Scientists have looked at anger and violence, though, and discovered genetic variations, expressed as concentrations of a particular messenger molecule in the brain, that are both congenital and predisposing to aviolenttemper.
That number found that Moussaoui's "unstable early childhood and dysfunctional family" resulted in him leaving home at a young age, and that Moussaoui's father had aviolenttemper and abused his family.